Extracted sugar-beet pulp and sucrose, two renewable materials as "hot" substrates for enzymatic synthesis of valuable saccharides

The goal of this thesis is the development of an integrated biotechnological process system for the low-cost and environmentally friendly production of valuable products (galacturonic acid and galactosyl-fructoside) from cheap renewable materials. With this purpose in view, the research was focussed on the subsequent two topics: a. Production of galacturonic acid, an interesting and valuable building block for pharmaceuticals, cosmetics and food ingredients from extracted sugar-beet pulp, for an efficient valorisation of this by-product of the sugar refining industry; b. Synthesis of a rare disaccharide, represented by the sucrose analogue galactosyl-fructoside (Gal-Fru) by using sucrose as substrate and monosaccharide galactose as acceptor in the transfructosylation reaction catalysed by FTF from B. subtilis. Essential aspects of this integrated multidisciplinary research approach are reaction engineering and analytical procedures as follows: - enzyme screening for selecting from several potential candidates of the most suitable two enzymes; - establishing optimal reaction conditions for both high yield and concentration of galacturonic acid and galactosyl-fructoside; - separation of the target products from the saccharide mixtures, in order to provide galacturonic acid and Gal-Fru on preparative scale; - kinetic characterisation of the galacturonic acid synthesis by degradation of extracted sugar-beet pulp; - analysis of the structure of Gal-Fru and the nature of the glycosidic bond; - FTF characterisation.